Which of the following pair is not isoelectronic species?
(At. no. Sm, 62; Er, 68: Yb, 70: Lu, 71; Eu, 63: Tb, 65; Tm, 69)
(At. no. Sm, 62; Er, 68: Yb, 70: Lu, 71; Eu, 63: Tb, 65; Tm, 69)
- (A) and
- (B) and
- (C) and
- (D) and ✓ Correct
Answer: (D)
Solution
Isoelectronic species have the same number of electrons. Let's calculate:
Since 63 ≠ 65, and are not isoelectronic. All other pairs have equal electron counts.
- : 65 - 2 = 63 electrons
- : 69 - 4 = 65 electrons
Since 63 ≠ 65, and are not isoelectronic. All other pairs have equal electron counts.
JEE Main · 2022 · 28 Jul 2022 · Shift 2 · Single correct option